a, Basic module, with an illustration of its internal actuation mechanism. b, Snapshots from the first 10 s showing how a four-module robot transforms when its modules swivel simultaneously. c, Sequence of frames showing the self-reproduction process, which spans about 2.5 min and runs continuously without human intervention, apart from the replenishing of building blocks at the two 'feeding' locations (circled in red). (For movie, see supplementary information.)
The video is surreal, the motion of the little blocks seems very organic somehow.
A modular machine made of four swiveling blocks uses electromagnets to reproduce itself in a matter of minutes. You have to give it pre-made fresh blocks and put them in a convenient location. This is definitely lowering the bar for self-reproduction, the blocks are complicated little devices themselves. People manage to reproduce themselves using fairly simple chemicals as buidling blocks, though we too require seven essential amino acids that we can't fabricate ourselves. As the authors themselves point out: "We circumvent the long-standing hurdle of what counts as self-replication by suggesting that self-replicability is not a binary property that a system either possesses or not, but is a continuum dependent on the amount of information being copied." Hence a strategy leading to more convincing self-reproduction might involve incrementally simplifying a system of rather complex building blocks, rather than starting from scratch with a satisfyingly elementary substrate.
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